强脉冲离子束材料表面改性研究进展

强脉冲离子束材料表面改性技术是正在发展中的新的材料表面改性技术。近四、五年来,我们围绕发展强脉冲离子束材料表面改性技术对其主要机制(强脉冲能量效应)、离子辐照诱发的热力学过程、表面熔坑现象及大面积均匀离子束技术开展了比较全面的基础性研究。研究表明,强脉冲离子束改性除了离子注入的元素掺杂效应外,其更可利用强脉冲能量沉积诱发的热力学效应,有望突破离子射程对改性层厚度的限制,并高效利用离子剂量和能量,成为新一代低成本、高效率、高生产率、实用化的离子束材料改性与合成工艺。本文对于上述研究的主要进展和相关问题进行了总结和评论。     

Isomer separation of Cu and Cu with a resonance ionization laser ion source

Radioactive copper isotopes were ionized with the resonance ionization laser ion source (RILIS) at the on-line isotope separator ISOLDE (CERN). Using the different hyperfine structure in the 3d¹⁰ 4s  ²S_1/2 – 3d¹⁰ 4p  ²P⁰_1/2 transition the low- and high-spin isomers of ⁷⁰Cu were selectively enhanced by tuning the laser wavelength. The light was provided by a narrow-bandwidth dye laser pumped by copper vapor lasers (CVL) and frequency doubled in a BBO crystal. The ground state to isomeric state intensity ratio could be varied by a factor of 30, allowing to assign gamma transitions unambiguously to the decay of the individual isomers. It is shown that the method can also be used to determine magnetic moments. In a first experiment for the 1⁺ ground state of ⁷⁰Cu a magnetic moment of (+)1.8(3) μ_N and for the high-spin isomer of ⁷⁰Cu a magnetic moment of (±)1.2(3) μ_N could be deduced.     

Study of doping uniformity of a 200 kV ion implanter by RBS and sheet resistance measurements

The ion implantation uniformity is of vital importance for an ion implanter.In this paper,we report the,uniformity measurement for a large current ion implanter(LC-16 type) by implanting of 190-keV Ar ions into Si to 3×1016 atoms/cm2,followed by Rutherford backscattering spectroscopy(RBS) and sheet resistance measurement providing quantitative information on spatial distribution of dopants.The implant doses obtained from RBS at selected points of the sample give a spatial uniformity of 5%,which are confirmed by the sheet resistance measurement.While sheet resistance is an indirect method for dose evaluation of ion-implanted samples,RBS provides a competent technique for calibration of the ion implantation system.And both measurements show that good uniformity can be achieved for the ion implanter by tuning of the scanning process.     

铬,钽离子束表面冶金合金的抗腐蚀机制

根据离子束表面冶金的特点，从合金成分、结构、缺陷、元素性质以及表面污染等方面系统地讨论了Ｃｒ、Ｔａ元素加入对金属腐蚀行为的影响。在此基础上，提出它们抑制腐蚀的综合模式，较好地解释了这类表面合金抗腐蚀的机制。     

利用离子注入技术研制新型抗辐照太阳电池

利用离子注入技术在电池表面层形成密集的垂直ＰＮ结，缩短光生载流子到达ＰＮ结的距离，提高ＰＮ结的收集效率，从而研制成一种新型的抗辐照太阳电池。     

离子束处理精密微型轴承滚珠的俄歇电子能谱和电子衍射分析

用离子束动态混合技术将Ｔｉ和Ｎ两种离子同时注入φ１．５７－１．６０ｍｍ的精密微型轴承滚珠。用俄歇电子能谱和电子衍射分析分别检验了注入离子在基体内的纵向分布和在球表面的均匀性。在辅助沉积Ｎ离子的能量为１００ｋｅＶ、注入剂量为３×１０＾１７ｉｏｎｓ／ｃｍ＾２的条件下，混合区宽度达１４０ｎｍ以上，同一球面的不均匀度〈１３％，球间的不均匀度〈１５％。表明在适当工艺条件下，对这种精密部件采用离子束表面优化改     

利用离子束技术及PECVD制备碳化硅

阐述利用离子注入、离子束增强沉积、反应离子束溅射及反应离子束辅助沉积等方法制备碳化硅薄膜的实验结果，并报道利用等离子体增强化学气相沉积技术制备可光致发光的非晶态α－ＳｉＣ：Ｈ薄膜的工作。     

A Monte Carlo study of surface sputtering by dual and rotated ion beams

Several, recently proposed methods of surface manufacturing based on ion beam sputtering, which involve dual beam setups, sequential application of ion beams from different directions, or sample rotation, are studied with the method of kinetic Monte Carlo simulation of ion-beam erosion and surface diffusion. In this work, we only consider erosion dominated situations. The results are discussed by comparing them to a number of theoretical propositions and to experimental findings. Two ion-beams aligned opposite to each other produce stationary, symmetric ripples. Two ion beams crossing at right angle will produce square patterns only, if they are exactly balanced. In all other cases of crossed beams, ripple patterns are created, and their orientations are shown to be predictable from linear continuum theory. In sequential ion-beam sputtering we find a very rapid destruction of structures created from the previous beam direction after a rotation step, which leads to a transient decrease of overall roughness. Superpositions of patterns from several rotation steps are difficult to obtain, as they exist only in very short time windows. In setups with a single beam directed towards a rotating sample, we find a non-monotonic dependence of roughness on rotation frequency, with a very pronounced minimum appearing at the frequency scale set by the relaxation of prestructures observed in sequential ion-beam setups. Furthermore we find that the logarithm of the height of structures decreases proportional to the inverse frequency.     

重离子辐照微生物效应及诱变育种进展

重离子束作为一种高效的、典型的诱变辐射源广泛用于生物育种。不同质量数、电荷数和不同能量的重离子束作用于生物细胞有特殊的过程和作用,其先后经历物理、化学和生物学三个阶段,最终引发终点生物学效应,如辐射低剂量超敏感现象,活性氧代谢变化等。本文重点探讨重离子束辐照微生物体后出现的主要终点生物效应,以及近年来重离子辐照微生物诱变育种在工农业等方面取得的成果。     

Preparation of Ne, Mg, Si, S, and Ar targets by ion implantation into thin carbon foils

The preparation of isotopically pure targets of ²⁰Ne, ²⁴Mg, ²⁸Si, ³²S, and ³⁶Ar by the implantation of 25-70 keV ions into carbon foils is described.     

Dynamic energy spectrum and energy deposition in solid target by intense pulsed ion beams

A method for analyzing the dynamic energy spectrum of intense pulsed ion beam (IPIB) was proposed.Its influence on beam energy deposition in metal target was studied with IPIB produced by two types of magnetically insulated diodes (MID).The emission of IPIB was described with space charge limitation model,and the dynamic energy spectrum was further analyzed with time-of-flight method.IPIBs generated by pulsed accelerators of BIPPAB-450 (active MID) and TEMP-4M (passive MID) were studied.The dynamic energy spectrum was used to deduce the power density distribution of IPIB in the target with Monte Carlo simulation and infrared imaging diagnostics.The effect on the distribution and evolution of thermal field induced by the characteristics of IPIB dynamic energy spectrum was discussed.     

低能高束流氩离子源的结构及性能

离子源技术是等离子体研究中的一项重要内容,而低能大束流源则是离子源技术研究中的一个重要方向,因为这样的源在离子束刻蚀、离子束溅射镀膜以及荷能粒子与物质相互作用方面都有广泛的应用;本文采用空心阴极空心阳极结构,用热阴极电子发射弧放电驱动并用磁场约束产生等离子体,用曲面发射引出离子束,研制成了氩气放电溅射离子源;研究了灯丝加热电流、弧压对弧流的影响和弧流与工作气体压力对离子束引出的影响规律.离子源的引出电压在0-4.0 kV之间连续可调,最大引出束流为100 mA,束斑面积为φ6.0 cm,以Ti为溅射靶时的最大溅射沉积率为0.45 nm/s,离子源可连续工作160 h.     

FIBSIM – dynamic Monte Carlo simulation of compositional and topography changes caused by focused ion beam milling

A new simulation program is presented for focused ion beam (FIB) induced sputtering in two-dimensional targets. The model combines dynamic Monte Carlo simulation of the collision cascades with cell-based topography simulation. This approach takes the nonlocal nature of the sputtering process into account, and treats doping, damage formation and compositional changes self-consistently with the evolution of the surface. Two applications are presented: erosion of a sample edge, and milling of a hole into a multilayer target.     

放射性示踪技术研究金,铂在新型大孔树脂HHY—10A上的离子交换行为

应用１９５ｍＰｔ、１９９Ａｕ放射性示踪剂研究了金、铂在一种新研制的大孔强碱性阴离子交换树脂上的离子交换行为。系统研究了吸附和洗脱的条件，包括吸附介质的成分和酸度、洗脱剂以及吸附和洗脱流速的影响等。应用此法从标准参考物质ＤＺΣ－１、ＤＺΣ－２中分离和浓集出Ａｕ、Ｐｔ，用ＩＣＰ－ＭＳ测定，分析结果与推荐值符合良好。     

On the NBI system for substantial current drive in a fusion power plant: Status and R&D needs for ion source and laser neutralizer

The requirements for the heating and current drive systems of a fusion power plant will strongly depend on the DEMO scenario. The paper discusses the R&D needs for a neutral beam injection system — being a candidate due to the highest current drive efficiency — for the most demanding scenario, a steady state tokamak DEMO. Most important issues are the improvement of the wall-plug efficiency from the present ∼25% to the required 50–60% by improving the neutralization efficiency with a laser neutralizer system and the improvement of the reliability of the ion source operation. The demands on and the potential of decreasing the ion source operation pressure, as well as decreasing the amount of co-extracted electrons and backstreaming ions are discussed using the ITER requirements and solutions as basis. A further concern is the necessity of cesium for which either the cesium management must be improved or alternatives to cesium for the production of negative ions have to be identified.